add timer and expose:

- duration
- start/stop switch
On start, it will display the remaining time instead of the watch

include/devices.h

@@ -46,6 +46,24 @@ namespace Devices {
                 strcmp("ON", msg) == 0 ? Display::changeHourFormat24(true) : Display::changeHourFormat24(false);
             }
         }).restoreStateFromCommand().build();
+    Number* displayTimerMqtt = Builder<Number>::instance(new Number{ "Display imer", "display_timer",
+            [](const char* msg) {
+                auto value = String{ msg }.toInt();
+                Display::Timer::timer = value;
+                displayTimerMqtt->updateState(value);
+            }
+        }).withMin(0).withMax(90).withStep(5).restoreStateFromCommand().build();
+    Switch* timerMqtt = Builder<Switch>::instance(new Switch{"Timer", "timer",
+            [](const char* msg) {
+                if (strcmp("ON", msg) == 0) {
+                    Display::Timer::start();
+                    timerMqtt->updateState(true);
+                 } else {
+                    Display::Timer::stop();
+                    timerMqtt->updateState(false);
+                 }
+            }
+        }).restoreStateFromCommand().build();
 
     auto button = 
         Builder<Button>::instance(new Button{"Restart", "restart",
@@ -82,8 +100,10 @@ namespace Devices {
             }).build()
         )
         .addSecondary(ledMqtt)
+        .addSecondary(timerMqtt)
         .addConfiguration(brightnessMqtt)
         .addConfiguration(hourFormatMqtt)
+        .addConfiguration(displayTimerMqtt)
         .addPreconfigured(HaESP::heapStats)
         .addPreconfigured(HaESP::restartInfo)
         .build();

include/display.h

@@ -13,7 +13,9 @@
 #define BRIGHTNESS_STEP 1
 #define BRIGHTNESS_NIGHT BRIGHTNESS_MIN
 #define BRIGHTNESS_DAY 11
-#define SECONDS(value) value*1000
+#define MILLISECONDS(value) value*TASK_MILLISECOND
+#define SECONDS(value) value*TASK_SECOND
+#define MINUTES(value) value*TASK_MINUTE
 #define DISPLAY_SENSOR_ITERATIONS 2
 #define DISPLAY_DELAY (SECONDS(2))
 
@@ -25,7 +27,7 @@ namespace Display {
     void displayHumidity();
     void drawTime();
     void drawColon(bool);
-    Task tDisplayTime(500, TASK_FOREVER, displayTime, &ts, false,
+    Task tDisplayTime(MILLISECONDS(500), TASK_FOREVER, displayTime, &ts, false,
         []() {
             drawTime();
             return true;
@@ -33,7 +35,7 @@ namespace Display {
         []() {
             drawColon(false);
         });
-    Task tDisplaySensor(5 * TASK_SECOND, DISPLAY_SENSOR_ITERATIONS, displayTemp, &ts, false,
+    Task tDisplaySensor(SECONDS(5), DISPLAY_SENSOR_ITERATIONS, displayTemp, &ts, false,
         []() {
             tDisplayTime.disable();
             return true;
@@ -49,7 +51,7 @@ namespace Display {
             return true;
         },
         []() {
-            tDisplayTime.enableDelayed(5 * TASK_SECOND);
+            tDisplayTime.enableDelayed(SECONDS(5));
         });
 
     bool hourFormat24 = false;
@@ -73,6 +75,29 @@ namespace Display {
         }
     }
 
+    namespace Timer {
+        int8 timer = 0, currentTimer = 0;
+
+        void start() {
+            currentTimer = timer;
+            auto displayTimer = []{
+                if (currentTimer >= 0) {
+                    clockDisplay.print(currentTimer--, DEC);
+                    clockDisplay.writeDisplay();
+                }
+            };
+            tDisplayTime.setInterval(MINUTES(1));
+            tDisplayTime.setCallback(displayTimer);
+            tDisplayTime.restart();
+        }
+
+        void stop() {
+            tDisplayTime.setInterval(MILLISECONDS(500));
+            tDisplayTime.setCallback(displayTime);
+            tDisplayTime.restart();
+        }
+    }
+
     void drawTime() {
         int displayHour = hourFormat24 ? hour() : hourFormat12();
         int displayMinute = minute();